Internet Engineering Task Force (IETF) K. Raza
Request for Comments: 7358 S. Boutros
Updates: 3212, 4447, 5036, 5918, 6388, 7140 L. Martini
Category: Standards Track Cisco Systems, Inc.
ISSN: 2070-1721 N. Leymann
Deutsche Telekom
October 2014
Label Advertisement Disciplinefor LDP Forwarding Equivalence Classes (FECs)
Abstract
The label advertising behavior of an LDP speaker for a given
Forwarding Equivalence Class (FEC) is governed by the FEC type and
not necessarily by the LDP session's negotiated label advertisement
mode. This document updates RFC 5036 to make that fact clear. It
also updates RFCs 3212, 4447, 5918, 6388, and 7140 by specifying the
label advertisement mode for all currently defined LDP FEC types.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7358.
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RFC 7358 Label Advert. Discipline for LDP FECs October 2014
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................22. Label Advertisement Discipline ..................................32.1. Update to RFC 5036 .........................................32.2. Specification for LDP FECs .................................43. Security Considerations .........................................44. IANA Considerations .............................................45. References ......................................................65.1. Normative References .......................................65.2. Informative References .....................................7
Acknowledgments ....................................................8
Authors' Addresses .................................................81. Introduction
The Label Distribution Protocol (LDP) [RFC5036] allows label
advertisement mode negotiation at the time of session establishment.
The LDP specification also dictates that only a single label
advertisement mode be negotiated, agreed upon, and used for a given
LDP session between two Label Switching Routers (LSRs).
The negotiated label advertisement mode defined in RFC 5036 and
carried in the LDP Initialization message is only indicative. It
indicates how the LDP speakers on a session will advertise labels for
some Forwarding Equivalence Classes (FECs), but it is not a rule that
restricts the speakers to behave in a specific way. Furthermore, for
some FEC types the advertising behavior of the LDP speaker is
governed by the FEC type and not by the negotiated behavior.
This document updates [RFC5036] to make that fact clear. It also
updates [RFC3212], [RFC4447], [RFC5918], [RFC6388], and [RFC7140] to
indicate, for each FEC type that has already been defined, whether
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RFC 7358 Label Advert. Discipline for LDP FECs October 2014
the label binding advertisements for the FEC are constrained by the
negotiated label advertisement mode or not. Furthermore, this
document specifies the label advertisement mode to be used for all
currently defined FECs.
2. Label Advertisement Discipline
To remove any ambiguity and conflict regarding a label advertisement
discipline among different FEC types sharing a common LDP session,
this document specifies a label advertisement discipline for FEC
types.
This document introduces the following types for specifying a label
advertisement discipline for a FEC type:
- DU (Downstream Unsolicited)
- DoD (Downstream on Demand)
- As negotiated (DU or DoD)
- Upstream ([RFC6389])
- Not applicable
- Unknown
2.1. Update to RFC 5036Section 3.5.3 of [RFC5036] is updated to add the following two
statements under the description of "A, Label Advertisement
Discipline":
- Each document defining an LDP FEC must state the applicability of
the negotiated label advertisement discipline for label binding
advertisements for that FEC. If the negotiated label
advertisement discipline does not apply to the FEC, the document
must also explicitly state the discipline to be used for the FEC.
- This document defines the label advertisement discipline for the
following FEC types:
+----------+----------+--------------------------------+
| FEC Type | FEC Name | Label Advertisement Discipline |
+----------+----------+--------------------------------+
| 0x01 | Wildcard | Not applicable |
| 0x02 | Prefix | As negotiated (DU or DoD) |
+----------+----------+--------------------------------+
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RFC 7358 Label Advert. Discipline for LDP FECs October 20142.2. Specification for LDP FECs
The label advertisement discipline for currently defined LDP FEC
types is listed in Section 4.
This document updates the respective RFCs in which these FECs are
introduced and defined.
3. Security Considerations
This document only clarifies the applicability of an LDP session's
label advertisement mode and hence does not add any LDP security
mechanics and considerations to those already defined in the LDP
specification [RFC5036].
4. IANA Considerations
This document mandates the specification of a label advertisement
discipline for each defined FEC type and hence IANA's "Forwarding
Equivalence Class (FEC) Type Name Space" registry under IANA's "Label
Distribution Protocol (LDP) Parameters" registry has been extended as
follows:
- Added a new column titled "Label Advertisement Discipline" with
the following possible values:
o DU
o DoD
o As negotiated (DU or DoD)
o Upstream
o Not applicable
o Unknown
- Made this document an additional reference for the registry itself
and for all affected registrations.
- Kept other columns of the registry in place and populated as they
were.
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